Tunnel lining machine



sept. 29, 1942. M, ROM l 2,297,099

TUNNEL LINING MACHINE Filed Feb. 8, 1940 sheets-sheet 1 Sept. 29, 1942.J. M. cROM 2,297,099

TUNNEL LINING MACHINE Filed Feb. a, 1940 3 sheets-sheet 2 n Jolaj'ow 3Mmw @M v A www Sept. 29, 1942. J. M. cRoM TUNNEL LINING MACHINE FiledFeb. 8, 1940 3 Sheets-Sheet 5 www Mlm-wf, y y

Patented Sept. 29, 1942 UNITED STATES PATENT OFFICE 14 Claims.

This invention relates to an apparatus for applying a coating of plasticmaterial to the walls dening a passageway in accordance with the processdescribed in my prior application Serial N0. 722,585 led April 26, 1934,now Patent No. 2,176,891, issued October 24, 1939. More specifically thepresent apparatus is an improvement over that described in my copendingapplication Serial No. 301,077 filed October 24, 1939, of which thisapplication is a continuation-impart. The improved machine of thisinvention is peculiarly adapted to the formation of mortar or cementcoatings on the walls dening a passageway such as a ditch, a tunnel, aconduit, or the like and is eminently suited to the coating of suchsurfaces with plastic materials in general such, for example, asplaster, asphalt, waxes, resins, gum or the like.

Prior to the inventions described in the applications noted above,mortar coatings were applied by hand, that is, by the use of a pneumaticprojecting device generally known as a Gunite or cement gun manuallydirected onto the surface to be covered. Even in coating small objects,hand operation of the projecting nozzle produces some unevenness of thecoating and requires the application of a considerable excess of thecoating material to assure thorough coverage. In coating large objectssuch as a ditch or a tunnel this unevenness and waste is greatlyincreased. Further, due to the uneven application, sand, which isintermixed with cement and water to form the mortar accumulates in smallpiles and a tendency to cause sand pockets and flaws in the coating isthe result. These are particularly undesirable when water is to flowthrough the coated passage, as they retard the flow and allow water toseep out and undermine the structure.

These difficulties have been substantially overcome by means of theapparatus and processes described in my prior applications. It is nowpossible by means of those previous inventions to produce a lining thatis smooth, even and free from flaws and sand pockets in an economicalmanner. Large savings in both labor and material are thereby achieved.The said prior inventions also provide for applying the coating inpredetermined variable thicknesses at one or more longitudinal sectionsin order to avoid the usual effects of wear or strain. Thus the bottomof a ditch may be provided with a thicker lining than that applied tothe sides of the ditch, whereby the greater effects of strain and Wearin this portion of the ditch are overcome.

In general, the apparatus of my invention comprises a machine thattravels along the ditch, tunnel or the like and carries upon an armextending from one end thereof the nozzle of a pneumatic mortarprojecting device. Preferably, the machine carries a prime moverconnected to means for driving the machine along the passage to becoated and to means for causing the nozzle carrying arm to rotate in themanner desired. Movement of the nozzle is such that the mortar or otherplastic material is applied to the internal surface of the wall deningthe passage in adjacent, partially overlapping strips each of whichextends transversely of the ditch or, in the case of a completelyenclosed passage such as a tunnel, the strips are arranged helicallyabout the interior of the passage.

Although very good results have been obtained in actual use of thedevice disclosed in the prior applications noted above, it has now beenfound that the same may be substantially improved and superior liningsformed by a certain combination of modifications described herein. Inuse of my earlier apparatus it has been found that as the nozzlecarrying arm rotates or oscillates about r the axis thereof, mortar isdeposited upon the surface to be coated and a substantial amount of sandrebounds and particles thereof are projected in all directions atrandom. This material tends to lodge at the bottom of the passage andmay accumulate in piles on the uncoated portion of the passage prior tothe portion upon which mortar is applied by the nozzle. When mortar isapplied over such an accumulation of loose sand, a pocket of materialhaving no ability to set firmly is incorporated in the lining. In orderto avoid such weak places in the resultant structure, the presentinvention provides a brush moving about the passage in the same generaldirection as the nozzle and slightly in advance thereof to break up andspread sand accumulations in such a manner that the same may beincorporated in the lining as an integral part thereof. Preferably themechanism is so formed with a pan and a guard apron adjacent the brushthat the rebounding sand will accumulate in the bottom of the pancarried by the machine for periodic removal by the operator. Theinvention also contemplates arranging the Wheels with respect to the panin such manner that the pan may be raised and lowered and that thepossibility of sand going to the bottom of the passage to be coatedthrough openings provided for the wheels will be substantiallyprevented.

It has also been found advantageous to use an air jet, either with thebrush or alone, in order to remove and distribute sand deposits inadvance of the jet.

Means are also provided to avoid weakening of the lining by particles ofsand which rebound to the surface of mortar already applied. The means,preferably a trowel, used for this purpose are also effective inimparting a smooth surface to the finished lining. According to theinvention the nozzle is followed by a screed to remove irregularitiescaused by projecting rivet heads or other inequalities in the surface tobe coated. This element of the machine is in the nature of a cuttingedge, similar to the edge of a trowel. The screed is preferably followedby the trowelling device noted above which imparts a smooth finish tothe lining and incorporates therein any loose sand lying upon theexposed surface.

Ordinarily mortar deposited in accordance with my invention isrelatively dry and the smoothing action of the trowel described above isrendered considerably more efficient if the surface of the lining ismoistened slightly by a jet moving in advance of the trowel.

These and other objects and advantages of the invention will be apparentfrom the following detailed discussion of a preferred embodiment of theinvention when considered in connection with the accompanying drawingswherein:

Figure 1 represents a horizontal section through a circular conduit withthe present ma chine situated therein, showing the relationship of theparts of a machine with respect to a lining being deposited in saidconduit;

Figure 2 is a vertical section through the conduit of Fig. 1, showingthe machine in elevation;

Figure 3 is a section on line 3-3 of Fig. 2;

Figure 4 is a section on line 4-4 of Fig. 2;

Figure 5 is a detail view of the edge of the pan showing the manner inwhich the same is adapted to operation in a passage having a wire meshreinforcing element arranged therein; and

Figure 6 is a cross-section on line 6-6 of Fig.. 5.

Referring specifically to Figures 1 and 2, which show the machine ofthis invention within a tubular conduit defined by a wall I0, upon whichis deposited a lining II, the device comprises side frame members I2 andsuitable cross beams I3 carrying the elements which apply and form thelining II. A pair of wheels I4 are mounted on the ends of an axle I5connected to each end of the framework by means of brackets I6.

A prime mover of any suitable design such as the internal combustionengine indicated generally at I1 is mounted on cross beam members I3. Itwill be obvious that the prime mover may be an electric or compressedair rriotor ac cording to the circumstances under which it is to beused. Shaft IB driven by the motor I1 operates a train of gears in gearbox I9 to drive shaft 20, upon which is mounted clutch 2I to furnishmotive power for the wheels I4 as desired by the operator through chain22 and sprocket 23, which sprocket is keyed to one of the axles I5. Apan 24 is carried below the framework of the machine to catch reboundingsand in the manner described above. The said pan is retained in itsdesired position by means of brackets 21 and 28 connected to rod 29,which rod is in turn connected with frame members I2 by arms 30 and 3|through shafts 32. Rotation and adjustment of the shafts 32 iscontrolled by manual operation of the lever 33 keyed to one of saidshafts. The two shafts are caused to move in unison by means of cranklevers 34 keyed to said shafts and interconnected with the lever 33 bymeans of said shafts and the rods 35. It will be seen that when thelever 33 is moved through a suitable arc rotation of the shaft 32 willraise or lower the pan 24 through the medium of arms 30 and 3| operatingupon the rod 29. An arcuate rack 36, or other suitable means forretaining the lever 33 in adjusted relation to the frame, is preferablyprovided.

Each of the wheels I4 is enclosed by a hood 36 formed integral with thepan 24, and each of the said hoods is provided with a slot 3l to permitraising and lowering of the pan 24 with respect to the rest of themachine.

That end of the pan 24 adjacent the nozzle and other apparatus forapplying and forming the coating I I is provided with an apron member 38fastened to said pan as by means of rivets 39 and having spring steelfingers 4I) extending beyond the edge of said pan. Figures 5 and 6illustrate the function of the fingers 40 in providing an excellent sealagainst the passage of rebounding sand to the space beneath pan 24, whenthe machine is being used to line a passageway in which a mesh typereinforcing element has been placed to strengthen the plastic liningapplied by the machine. It has been found advisable to raise the pansomewhat above the bottom of the passageway in moving the machine fromone region to be coated to another region to be coated. Preferably thefingers are so formed that they will not contact the bottom of thepassageway when the pan is so raised. It will be understood that theapron 38 is not an absolute essential to successful operation but it hasbeen found that this type of structure contributes to the operation ofthe other elements to be hereinafter described to such an extent thatthe said apron is deemed to be highly advisable in the presentstructure.

Those elements of the device for preparing the surface of the passagewayID, applying the lining II thereto and finishing said lining are mountedupon a projecting end of a hollow shaft 4I having a conduit 42 fortransporting mortar and a pipe 43 adapted to carry water disposedtherein. Preferably, means are also provided for transporting compressedair through said shaft 43. The said shaft 4I is caused to rotate aboutits axis by power supplied thereto from drive shaft I8 through gears 44and 45. Although my prior applications describe specifically a rna chineof the present type in which the mortar applying nozzle precedes theheavier portions of the machine in the direction of travel thereof, itwill be noted that those applications also disclose the concept of soconstructing the device that the mortar applying nozzle follows thewheel carried frame. According to the present invention, this latterexpedient is deemed preferable and the machine is adapted to move insuch direction that the lining is applied to portions of the passagealready traversed by the wheel carried frame, Mounted on the shaft 4I torotate therewith is a mortar applying nozzle 46 operating insubstantially the manner disclosed in my prior applications. Mortarconveyed thereto through pipe 42 is projected together with watersupplied through pipe 43 onto the inner surface of the wall IU to formthe lining II.

EARHENVVAHF. APPARATUS.

As the nozzle 46 revolves, applying the lining II, sand rebounds fromthe surface treated in all directions. In order that piles of such sandmay not accumulate under the lining applied, there is provided a brush4l mounted on a spring arm 48 connected to the shaft 4I to rotatetherewith. As the machine operates, the brush 4l disturbs anddistributes sand deposits over the inner surface of the wall I Il inorder that said sand may be incorporated in the lining I I as applied bythe nozzle 46 immediately following said brush. A similar result may beobtained by the use of an air jet, such as 49, connected to a source ofcompressed air, not shown, either from a small air pump driven by themotor ll or from a remote supply of compressed air through the shaft 4Iin the manner discussed above. In order to obtain best results I havefound it is advisable to use both the brush 4l and the air jet 49 incombination, since the brush loosens and partially distributes sandwhich is thereafter entirely removed from the path of the nozzle by theair jet 49.

As noted above, rivet heads and other irregularities on the innersurface of the Wall Ill will tend to cause corresponding irregularitieson the inner surface of the lining II. These projections, which tend toincrease the resistance to the flow of uid within the finished passageare advantageously removed by means of a screed 50 having a sharp edge lcarried by an arm 52 on the shaft 4I. Any such device that presupposes atrue circular cross section of the passage is doomed to failure and itis therefore necessary that some provision be made for adapting thescreed to follow irregularities in outline of the passage.

In the present embodiment of the invention this result is achieved bymounting the screed 50 on a shaft 53 mounted for relative slidingmovement within a sleeve 54. There is provided a spring within thesleeve 54 which tends to urge the shaft 53 in a direction to cause thescreed edge 5I to move toward the inner surface of the lining II with aforce sufficient to accomplish the desired result.

As a final step in finishing the surface of the lining II a trowel 55follows the screed about the inner surface of said lining. This trowelis also spring mounted, as on spring arms 56, in order that it shall beself-adjusting. Preferably a rod 5l is provided for the purpose ofmaintaining the trowel at a suitable angle with respect to the surfaceof the lining II. As a general rule, the mortar is applied by the nozzle46 in a relatively dry condition and the surface thereof is usuallysubject to troweling only with considerable difficulty. The inventiontherefore preferably includes a water spray jet 58 supplied from thepipe 43 by a suitable connection, not shown. Both the water jet 58 andthe spring arms 56 carrying the trowel 55 are mounted upon a suitablearm 59 connected to the shaft 4I for rotation therewith.

It will be seen that as the machine moves through the passage defined bythe wall I0 (moving to the right in Figures 1 and 2) the sand reboundingfrom the mortar applied by nozzle 46 is projected either toward theunlined portion of the passage to be collected by pan 24 or distributedby brush 4'I and jet 49 or the sand is projected upon the lining alreadylaid and is incorporated in that lining by the passage thereover oftrowel 55. It also is apparent that both the brush 4l and the air jet 49are practically 75 essential to successful collection and distributionof the rebounding sand when the machine is used in a passage lined witha mesh reinforcing element such as that shown in Figures 5 and 6. Insuch case the action of the brush and air jet cause a. portion of thesand to be carried over the apron 38 into the pan 24, while anotherportion is distributed to the left of the brush (Figures 1 and 2) to beincorporated in the finished lining.

The screed following the nozzle cuts off irregular projections in theyapplied lining and leaves the material so removed in a loose conditionsuch that it is readily worked into the finished surface by the trowel55. It will therefore be seen that each of the improving elements nowformed as a part of the basic structure disclosed in my priorapplications contributes to the single result of applying to the wall I0a strong, smooth surfaced lining I I. Thus the action of the brush andair jet is of comparatively minor value unless there is provided meansfor collecting loose sand on that side of the brush remote from thenozzle and a means, such as trowel 55, on the other side of the brush.for working the rebound sand into the finished surface. But the actionof the trowel will necessarily be rendered less efficient unless thatelement is preceded by some such device as the screed 50 to removeirregularities from the surface.

It will be understood that the present specific disclosure is presentedas illustrative of a preferred embodiment and that numerousmodifications may be made therein with the view to adapting the machineto any particular state of circumstances. By suitable modification ofthe means for driving the element carrying the nozzle and other movableparts, the device is readily adapted to the lining of passageways otherthan the circular conduits here described. A more detailed discussion ofsuch modifications is given in my prior applications noted above, towhich those skilled in the art are referred.

I claim:

1. In a machine for applying a coating to the inside side of a vpassagehaving a wheel carried horizontal frame and a mortar projecting nozzlemounted for rotary motion at one end thereof, a pan below said framehaving an apron at the end thereof adjacent said nozzle comprisingspring fingers extending over the edge of said pan and flared outwardly.

2. In a machine for applying a coating to the inside of a passage havinga wheel carried horizontal frame and a mortar projecting nozzle mountedfor rotary motion at one end thereof, means for distributing sandrebounding from mortar applied by said nozzle comprising a brush mountedfor rotation intermediate said nozzle and said frame.

3. In a machine for applying a coating to the inside of a passage havinga wheel carried horizontal frame and a mortar projecting nozzle mountedfor rotary motion at one end thereof, means for distributing sandrebounding from mortar applied by said nozzle comprising an air jetmounted for rotation intermediate said nozzle and said frame.

4. In a device for lining a substantially circular passage of givenradius; the combination of a substantially horizontal frame, a rotatableshaft extending longitudinally and projecting from one end of said frameand mounted for rotation thereon, wheels to carry said frame alignedwith said shaft, the distance from the outside of said -wheels to theaxis of said shaft being substantially equal to but not in excess ofsaid given radius, adjustable mounting means connecting said frame andsaid wheels, means to rotate said shaft, means to rotate at least one ofsaid wheels to drive said device, an arcuate pan mounted below saidframe substantially parallel with the axis of said shaft and havingrecesses for said wheels, said pan being provided at the end thereofbelow the end of said frame from which said shaft projects with aplurality of spring fingers extending over the edge of said pan andbeing flared outwardly, a nozzle for applying a plastic material to theinner surface of said passage mounted on said shaft for rotationtherewith in a plane at right angles to the axis thereof and spaced fromsaid frame, means for supplying said plastic material to said nozzle, abrush mounted for rotation with said shaft in a plane at right angles tosaid axis intermediate said fingers and the said plane of said nozzle,an air jet mounted for rotation with said shaft in a plane parallel toand adjacent the said plane of said brush, means for supplying air underpressure to said jet, said brush and said air jet being spaced radiallyfrom the axis of said shaft a distance approximately equal to but not inexcess of said given radius, a trowel mounted for rotation with saidshaft in a plane Aparallel to the said plane of said nozzle and spacedtherefrom on the side thereof remote from said frame, and a screedmounted for rotation with said shaft in a plane parallel to andintermediate the said planes of said nozzle and said trowel, said screedhaving its portion most remote from said shaft in the form of an edgeparallel to said shaft, the radial distance of said screed and saidtrowel from said axis -being substantially equal to said given radiusminus the thickness of the plastic lining applied by said nozzle.

5. In a device for lining a substantially circular passage of givenradius; the combination of a substantially horizontal frame, a rotatableshaft extending longitudinally and projecting from one end of said frameand mounted for rotation thereon, wheels to carry said frame alignedwith said shaft, the distance from the outside of said -wheels to theaxis of said shaft being substantially equal to but not in excess ofsaid given radius, mounting means connecting said frame and said wheels,means to rotate said shaft, means to rotate at least one of said wheelsto drive said device, an arcuate pan mounted below said framesubstantially parallel with the axis of said shaft, said pan beingprovided at the end thereof below the end of said frame from which saidshaft projects with a plurality of spring fingers extending over theedge of said pan and being flared outwardly, a nozzle for applying aplastic material to the inner surface of said passage mounted on saidshaft for rotation therewith in a plane at right angles to the axisthereof and spaced from said frame, means for supplying said plasticmaterial to said nozzle, a brush mounted for rotation with said shaft ina plane at right angles t said axis intermediate said fingers and thesaid plane of said nozzle, and an air jet mounted for rotation with saidshaft in a plane parallel to and intermediate the said planes of saidbrush and said nozzle, said brush and said air jet being spaced radiallyfrom the axis of said shaft a distance approximately equal to but not inexcess of said given radius.

6. In a device for lining a substantially circular passage of givenradius; the combination of a substantially horizontal frame, a rotatableshaft extending longitudinally and projecting from one end of said frameand mounted for rotation thereon, wheels to carry said frame alignedwith said shaft, the distance from the outside of said wheels to theaxis of said shaft being substantially equal to but not in excess ofsaid given radius, mounting means connecting said frame and said wheels,means to rotate said shaft, means to rotate at least one of said wheelsto drive said device, an arcuate -pan mounted below said framesubstantially parallel with the axis of said shaft, said pan beingprovided at the end thereof below the end of said frame from which saidshaft projects with a plurality of spring ngers extending over the edgeof said pan and being flared outwardly, a nozzle for applying a plasticmaterial to the inner surface of said passage mounted on said shaft forrotation therewith in a plane at right angles to the axis thereof andspaced from said frame, means for supplying said plastic material tosaid nozzle, a ybrush mounted for rotation with said shaft in a plane atright angles to said axis intermediate said fingers and the said planeof said nozzle said brush .being adjustably positioned so as to beadapted to brush the surface of the passage.

7. In a device for lining a substantially circular passage of givenradius; the combination of a substantially horizontal frame, a rotatableshaft extending longitudinally and projecting from one end of said frameand mounted for rotation thereon, wheels to carry said frame alignedwith said shaft, the distance from the outside of said wheels to theaxis of said shaft being substantially equal to but not in excess ofsaid given radius, mounting means Iconnecting said frame and saidwheels, means to rotate said shaft, :means to rotate at least one ofsaid wheels to drive said device, an arcuate pan mounted below saidframe substantially parallel with the `axis of said shaft, said panbeing provided at the end thereof below the end of said frame from whichsaid shaft projects with a plurality of spring lingers extending overthe edge of said pan and being flared outwardly, a nozzle for applying aplastic material to the inner surface of said passage mounted on saidshaft for rotation therewith in a plane at right angles to the axisthereof and spaced from said frame, means for supplying said plasticmaterial to said nozzle, and an air jet mounted for rotation with saidshaft in a plane at right angles to said axis intermediate said ngersand the said plane of said nozzle.

8. In a device yfor lining a substantially circular passage of givenradius; the combination of a substantially horizontal frame, a rotatableshaft extending longitudinally and projecting from one end of said frameand mounted for rotation thereon, wheels to carry said frame alignedwith said shaft, the distance from the outside of said wheels to theaxis of said shaft being substantially equal to but not in excess ofsaid given radius, mounting means connecting said frame and said wheels,means to rotate said shaft, means to rotate at least one of said wheelsto drive said device, a nozzle for applying a plastic material to theinner surface of said passage mounted on said shaft for rotationtherewith in a plane at right angles to the axis thereof and spaced fromsaid frame, means for supplying said plastic material to said nozzle anda screed mounted for rotation with said shaft in a plane parallel to thesaid plane of said nozzle and spaced therefrom on the side thereofremote from said frame, said screed having its portion most remote fromsaid shaft in the form of an edge parallel to said shaft and .be-

ing resiliently mounted for movement of said edge toward and away fromsaid axis.

9. In a device for lining a substantially circular passage of givenradius; the combination of a substantially horizontal frame, a rotatableshaft extending longitudinally and projecting from one end of said frameand mounted for rotation thereon, wheels to carry said frame alignedwith said shaft, the distance from the outside of said wheels to theaxis of said shaft being substantially equal to but not in excess ofsaid given radius, mounting means connecting said frame and said wheels,means to rotate said shaft, means to rotate at least one of said wheelsto drive said device, a nozzle for applying a plastic material to theinner surface of said passage mounted on said shaft for rotationtherewith in a plane at right angles to the axis thereof and spaced fromsaid frame, means for supplying said plastic material to said nozzle, atrowel mounted for rotation with said shaft in a plane parallel to thesaid plane of said nozzle and spaced therefrom on the side thereofremote from said frame and means for spraying water to said innersurface of said passage mounted for rotation with said shaft in a planeparallel to and intermediate the said planes of said nozzle and saidtrowel.

10. In a device for lining a substantially circular passage of givenradius; the combination of a substantialy horizontal frame, a rotatableshaft extending longitudinally and projecting from one end of said frameand mounted for rotation thereon, wheels to carry said frame alignedwith said shaft, the distance from the outside of said wheels to theaxis of said shaft being substantially equal to but not in excess ofsaid given radius, mounting means connecting said frame and said wheels,means to rotate said shaft, means to rotate at least one of said wheelsto drive said device, a nozzle for applying a plastic material to theinner surface of said passage mounted on said shaft for rotationtherewith in a plane at right angles to the axis thereof and spaced fromsaid frame, means for supplying said plastic material to said nozzle, atrowel mounted for rotation with said shaft in a plane iparallel to saidplane of said nozzle and spaced therefrom on the side thereof remotefrom said frame, and a screed mounted for rotation with said shaft in aplane parallel to and intermediate said planes of said nozzle and saidtrowel, said screed having its portion most remote from said shaft inthe form of an edge parallel to said shaft, the radial distance of saidscreed and said trowel from said axis being substantially equal to saidgiven radius minus the thickness of the plastic lining applied by saidnozzle.

11. In a device for lining a substantially circular Ipassage of givenradius; the combination of a substantially horizontal frame, a.rotatable shaft extending longitudinally and projecting from one une bilHUUHI end of said frame and mounted for rotation thereon, wheels tocarry said frame aligned with said shaft, the distance from the outsideof said wheels to the axis of said shaft being substantially equal to-but not in excess of said given radius, mounting means connecting saidframe and said wheels, means to rotate said shaft, means to rotate atleast one of said wheels to drive said device, a trowel mounted forrotation with said shaft in a plane parallel to the said plane of saidnozzle and spaced therefrom on the side thereof remote from said frame,a screed mounted for rotation with said shaft in a plane parallel to andintermediate the said planes of said nozzle and said trowel, said screedhaving its portion most remote from said shaft in the form of an edgeparallel to said shaft, the radial distance of said screed and saidtrowel from said axis being substantially equal to said given radiusminus the thickness of the plastic lining applied by said nozzle, andmeans for spraying water to the surface of said lining mounted forrotation with said shaft in a plane parallel to and intermediate thesaid planes of said trowel and said screed.

12. In a machine for applying a coating to the inside of a passagehaving a wheel carried horizontal frame and a mortar projecting nozzlemounted for rotary motion at one end thereof, means for distributingsand rebounding from mortar applied by said nozzle comprising a brushmounted for rotation intermediate said nozzle and said frame, and a panhaving a marginal portion located near the path of movement of saidbrush, for receiving surplus sand and the like distributed thereby saidbrush and pan being located adjacent the surface of the passage to belined.

13. In a machine for applying a coating to the inside of a passagehaving a wheel carried horizontal frame and a mortar projecting nozzlemounted for rotary motion at one end thereof, means for distributingsand rebounding from mortar applied by said nozzle comprising an air jetmounted for rotation intermediate said nozzle and said frame, and a panhaving a marginal portion located near the path of movement of said jet,for receiving surplus sand and the like distributed thereby said jet andsaid pan being located adjacent the surface of the passage to be lined.

14. In a machine for applying a coating to the inside of a passagehaving a horizontal frame Imounted upon 'wheels and a mortar projectingnozzle mounted for rotary motion at one end thereof, a screed mountedfor rotation on the side of said nozzle remote from said frame,comprising an edge parallel to the axis of rotation thereof, said edgebeing adapted to be spaced inwardly from the bottom of the wheels adistance equal to the thickness of the lining being applied.

JOHN M. CROM.

